Teen, 15, charged with murder in mass killing of parents and three children in tony Seattle suburb

A 15-year-old boy has been charged with murder, three days after he allegedly shot his parents and three young siblings in a bloody scene at their luxurious Washington state mansion.

According to the King County Prosecutor's Office, prosecutors on Thursday charged the teenage gunman, who could not be identified because of his age, with five counts of aggravated first-degree murder and one count of attempted first-degree murder.

The teen could face life in prison if charged as an adult, prosecutors said.

The bodies of Mark and Sarah Humiston and three of their children, ages 6, 9 and 13, were found riddled with bullets around 5 a.m. Monday in the family's $2 million home in the Seattle suburb of Fall City .

A sixth victim, an 11-year-old girl, was shot twice and survived the horrific massacre, charging documents show.

Officers responded to the Lake Alice Road home – a stunning waterfront property – after receiving a 911 call from the suspected murderous teenager, who claimed his younger brother killed his family and then committed suicide out of fear at what he saw getting caught by pornography.

At the same time, police received a 911 call from a neighbor reporting that the 11-year-old survivor had been shot and was bleeding from his neck and hand, identifying the teenager as the shooter.

Officers then found the lifeless bodies of the parents and minor victims in the home, prosecutors said, and immediately took the teen into custody.

The alleged killer's sister managed to escape the house during the massacre and was eventually taken to Harborview Medical Center in Seattle after receiving medical attention from a neighbor.

The sole survivor was released from the hospital on Wednesday, a hospital spokesperson confirmed to USA Today.

Defense attorney Amy Parker described the teenager, who has no criminal record, as a young boy who “enjoys mountain biking and fishing.”

The devastated community of about 2,000 people – reeling from the shocking quintuple murder – held a candlelight vigil for the murdered family, which some had described from the outside looking in as “perfect”.

“It hits me really hard,” said Pastor Carrie Bland, who organized a candlelight vigil at Fall City Methodist Church on Tuesday evening, KOMO News reported.

“I think not only about the loss of children, but also the parents and the impact that that has. It impacts the community because each person touches multiple people.”

Humiston, 43, was a longtime electrical engineer at Hargis Engineers in Seattle, and his wife, 42, was reportedly a nurse, although it is unclear whether she was still practicing.

The 15-year-old is being held in secure custody at the Clark Child and Family Justice Center in Seattle.

He is due back in court on Friday.